Legume Genomics and Genetics 2025, Vol.16, No.1, 11-22 http://cropscipublisher.com/index.php/lgg 18 them out, you can knock them out, just like playing with building blocks. However, in actual operation, it is not that simple. Issues such as delivery efficiency and off-target effects still need to be gradually optimized. But it cannot be denied that this technology has ushered in a new era for crop breeding-not only can it quickly introduce beneficial mutations, but also repair those defective genes that affect drought resistance. Although its application on soybeans is still in the laboratory stage at present, who wouldn't say it's amazing when they see this potential? Gene editing technology has indeed played a new role in crop breeding in recent years, especially the CRISPR-Cas9 "molecular scissors". In addition to its impressive performance on soybeans, staple crops such as rice and wheat have also tasted the sweetness (Manavalan et al., 2009). Interestingly, combining this new technology with traditional breeding has yielded surprisingly good results-GWAS first locates drought resistant genes, CRISPR then precisely edits them, and finally screens them using conventional breeding methods. With the entire process, the breeding cycle can be shortened by several years. A study in 2021 demonstrated the power of this combination punch (Hasan et al., 2021), which not only improved drought resistance but also decreased yield. However, it is still too early to completely replace traditional methods, as practical issues such as field performance and regulatory approval need to be addressed step by step. But it cannot be denied that this technology provides new ideas for addressing the food security challenges brought by climate change, although there are still many obstacles to overcome on the road to promotion. 7 Challenges and Future Research Directions 7.1 Challenges in phenotypic data collection Measuring the drought resistance of soybeans is not that simple in practice. Those key indicators-such as root development, leaf wilting degree, etc.-are particularly troublesome to measure, and data from different plots and different years often do not match (Manavalan et al., 2009). Take the root system for example. Although everyone knows that it is particularly important for drought resistance, every time a measurement is made, the plant has to be pulled out by the roots, making it impossible to continuously track the changes of the same plant. The traditional manual measurement method is slow and prone to errors. Often, after working hard for a long time, the data obtained may not be reliable. Although there are some new technologies that can offer assistance now, to truly establish a large-scale and high-quality phenotypic database, many difficulties still need to be overcome. Now there are finally some new techniques for measuring soybean drought resistance, and those high-tech phenotype platforms have indeed been of great help (Kim et al., 2023a). For example, using cameras to automatically capture the growth process of plants, or installing sensors to monitor water conditions in real time, these non-destructive methods are much stronger than before-there is no need to uproot plants, and the same batch of materials can be tracked from seedling stage to maturity stage. However, to be honest, these new technologies need to be further adjusted when applied to drought resistance research in soybeans, as soybeans are quite unique and have different responses to drought at different growth stages. Recently, research has been attempting to combine these automated phenotype data with GWAS analysis. Although it is still in the exploratory stage, if it can be standardized, it will be much more convenient for drought resistant breeding in the future. Of course, practical issues such as equipment costs and data analysis algorithms also need to be considered, but at least we have seen the direction now. 7.2 Complexity of genetic regulatory networks for drought resistance traits The matter of soybeans' drought resistance is simple, but it's actually very complicated. A study in 2022 found (Ouyang et al., 2022) that merely finding a few QTLS is far from enough. These loci are interlinked to form a complex genetic network. Look, some genes are responsible for allowing cells to accumulate more proline to retain water, some control the root system to grow deeper, and others regulate the level of ABA hormone-these mechanisms each have their own responsibilities, but they have to work in coordination with each other. Just like a symphony orchestra, it is not enough to merely understand the sheet music of each musician; the key is to figure out how they play in coordination. Although many drought-resistant genes have been identified now, scientists are still scratching their heads over how these genes interact with each other. To completely crack this genetic code, it is estimated that it will still take some more years of effort.
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